Card files with guide rails such as sold under the ROLODEX name are available in many sizes and styles for many uses. Each card in such a file has a bottom region with a pair of notches that can fit removably over a pair of guide rails so that cards can readily be inserted, removed, and rearranged. Otherwise, the cards can pivot leaf-like on the rails so that the cards can be fingered through for quick access and viewing.
I have devised a window envelope usable with such guide rail card files for storing and filing small, thin objects that are viewably presented. My window envelope reliably holds objects against spilling out of the file and makes the objects easily viewable as the file is leafed through. Also, by being adapted to standard guide rail card files, my viewing envelopes can take advantage of the convenience and versatility of such files.